This invention is concerned with a method of controlling the temperature of a mould during the manufacture of moulded articles wherein a portion of the mould is moved between a mould open position thereof and a mould closed position thereof.
In the manufacture of many moulded articles, it is necessary to control the temperature of the mould used. For example, in the manufacture of glassware containers, the mould must be maintained in a specific temperature range to enable satisfactory articles to be produced. To achieve this the mould is cooled during a portion of each moulding cycle, the duration of this cooling being determined by an operator and adjusted in accordance with the quality of the articles produced. It has long been recognised that operator control of the mould temperature controlling means is undesirable because it is dependent on the skill of the operator and, in any case, causes delays as the need for an adjustment may take some time to become apparent. Attempts have, therefore, been made to provide better control by measuring the mould temperature automatically and either automatically controlling the cooling means or displaying the temperature so that the operator can adjust the cooling means in response to temperature changes. These attempts have, however, not been fully successful because of difficulties in obtaining the temperature of the mould. If electrical temperature reading apparatus is embedded in a mould portion, the connections thereto are subject to damage and the readings are affected by electrical noise created by the mould movements. Furthermore, temperature readings based on infra-red radiation received from the outside of the mould are subject to interference from reflected radiation and are difficult to measure because of the low levels of radiation available.
This invention has the object of providing a method of controlling the temperature of a mould in which the temperature of the mould is senses reliably and accurately.